Efficacy and Safety of GNT0003 Following Imlifidase Pre-treatment in Severe Crigler-Najjar Syndrome

Main Inclusion Criteria: 1. Severe Crigler-Najjar syndrome requiring ≥ 6 hours/ day of phototherapy 2. Molecular confirmation of mutation in the UGT1A1gene by DNA sequencing 3. Detectable serum neutralizing antibodies against AAV8 4. Laboratory parameters value not clinically significant 5. Highly effective method of contraception 6. Affiliated to or a beneficiary of a health care system Exclusion Criteria: 1. Participation in another interventional trial within 6 months prior to start of clinical trial intervention and during the whole clinical trial 2. Fibrosis score ≥ 3 (METAVIR) or 10 kPa (FibroScan®) 3. Liver transplantation 4. Significant underlying liver disease, chronic hepatitis B, C and/or infected with Human immunodeficiency virus 5. Any other clinically significant illness 6. Uncontrolled hyperlipidemia. 7. History of major thrombotic events, active peripheral vascular disease, proven hypercoagulable conditions, 8. History or presence of thrombotic thrombocytopenic purpura (TTP) or known familial history of TTP 9. Prior or current treatment with Gene therapy, cell based therapy, CRISPR/Cas9 or any other form of gene editing, imlifidase